1. Field of the Invention
The present invention relates to a paper pick-up mechanism of an automatic document feeder used for a scanning device, a photocopying machine, a printing machine, or a faxing machine etc.
2. Description of the Related Prior Art
An automatic document feeder (ADF) is mounted on an image capturing device or a printing device, so that multiple sheets of papers can be continuously input. The paper tray in the ADF equipment is usually arranged with an inclined angle greater than 15 degrees, whereby when the paper is placed in the paper tray, it can slide into a paper stand-by position by its own weight. This kind of inclined design has the function of feeding paper automatically. However, it occupies a large space.
The closest prior art of which the applicant is aware is disclosed in U.S. Pat. No. 5,344,134, which disclosed an automatic document feeder of a platform type.
In the automatic document feeder of an inclined type or a platform type, the sensor detects the paper when the paper is fed, then, a power device, such as a motor, supplies power to drive a link mechanism or lever member, so that a pick-up roller sways to and contacts with the paper automatically, so as to feed paper automatically. After all of the papers are input, the sensor detects that there is no paper, the motor rotates reversely to drive the link mechanism or lever member, so that the pick-up roller may be lifted to return to the stand-by position, thereby facilitating the user placing the paper again.
In such a manner, the pick-up roller is moved by the motor rotating normally or reversely to drive the link mechanism or lever member. Therefore, the design of the link mechanism or lever member has to be precise, and has to co-operate with other detecting and control members and related circuits, causing the design to be complicated. In addition, after the automatic document feeder accomplishes feeding papers, the motor has to rotate reversely to drive the link mechanism or lever member for lifting the pick-up roller, causing the motor to be frequently used.
The present invention provides a design which employs the action of a friction being converted into a torque, so that a frame provided with a friction member module can away in a lever manner, thereby automatically feeding papers.
For achieving the above objective, a friction member module is frictionally and rotatably mounted on a frame, and one face of the friction member module is provided with a friction face rested on the frame. When the friction member module is rotated, the friction between the frame and the friction member module exerts a torque action on the frame, so that the frame can be swayed by pivot shafts.
The friction member module may be a friction block, or any member mounted on the frame, such as an automatic paper feeding roller, a pick-up roller, or a belt for connecting the automatic paper feeding roller and the pick-up roller.
When there is no paper, one end of the frame can be lifted by a lever action, thereby facilitating the user placing the paper again. The frame may be provided with a counterweight which acts so that one end of the frame can be lifted automatically when there is no paper, thereby facilitating the user placing the paper again. The frame can also be lifted automatically by an elastic member.
The counterweight may be provided with a plurality of detachable adjusting counterweight units, thereby facilitating adjusting a counterweight proportion required for adjusting the lever motion of the frame.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.